ABSTRACT This paper reports on an empirical performance analysis of four modal theorem provers on benchmark suites of randomly generated formulae. The theorem provers tested are the Davis-Putnam-based procedure KSAT, the tableaux-based system KRZIS, the sequent-based Logics Workbench, and a translation approach combined with the first-order theorem prover SPASS. Our benchmark suites are sets of multi-modal formulae in a certain normal form randomly generated according to the scheme of Giunchiglia and Sebastiani [GS 96a, GS 96b]. We investigate the quality of (...) the random modal formulae and show that the scheme has some shortcomings, which may lead to mistaken conclusions. We propose improvements to the evaluation method and show that the translation approach provides a viable alternative to the other approaches. (shrink)

다산 역학의 성립과 정수, 그리고 그 경학적.사상사적의의를 논구한 저술.

현대철학의 핵심문제로 제시되어온 주체의 개념을 유 럽철학사의 맥락으로 논한 저서.

This paper considers a new class of agent dynamic logics which provide a formal means of specifying and reasoning about the agents activities and informational, motivational and practical aspects of the behaviour of the agents. We present a Hilbert-style deductive system for a basic agent dynamic logic and consider a number of extensions of this logic with axiom schemata formalising interactions between knowledge and commitment (expressing an agent s awareness of her commitments), and interactions between knowledge and actions (expressing no (...) learning and persistence of knowledge after actions). The deductive systems are proved sound and complete with respect to a Kripke-style semantics. Each of the considered logics is shown to have the small model property and therefore decidable. (shrink)

Quasi-Nelson logic (QNL) was recently introduced as a common generalisation of intuitionistic logic and Nelson's constructive logic with strong negation. Viewed as a substructural logic, QNL is the axiomatic extension of the Full Lambek Calculus with Exchange and Weakening by the Nelson axiom, and its algebraic counterpart is a variety of residuated lattices called quasi-Nelson algebras. Nelson's logic, in turn, may be obtained as the axiomatic extension of QNL by the double negation (or involutivity) axiom, and intuitionistic logic as the (...) extension of QNL by the contraction axiom. A recent series of papers by the author and collaborators initiated the study of fragments of QNL, which correspond to subreducts of quasi-Nelson algebras. In the present paper we focus on fragments that contain the connectives forming a residuated pair (the monoid conjunction and the so-called strong Nelson implication), these being the most interesting ones from a substructural logic perspective. We provide quasi-equational (whenever possible, equational) axiomatisations for the corresponding classes of algebras, obtain twist representations for them, study their congruence properties and take a look at a few notable subvarieties. Our results specialise to the involutive case, yielding characterisations of the corresponding fragments of Nelson's logic and their algebraic counterparts. (shrink)

Forcing extensions yield models of ZFC in which a long sequence of club subsets of ω 1 has the following property: every subsequence of size ℵ 1 has a finite intersection.

This article argues that the causal loops that occur in some time-travel scenarios and in certain solutions of the theory of relativity are no more mysterious than the infinitely descending causal chains familiar from Newtonian mechanics.

This article presents the new German law on advance directives from 1 September 2009. The history of the parliamentary process of this law is described, the present regulations are explained, their relevance for medical practice discussed and shortcomings are identified. Finally, the new law is compared with other regulations in the international context. Previously established legal practice in Germany has now become largely confirmed by the new law: An advanced directive must be respected in any decision concerning medical treatment, regardless (...) of the stage of the illness. It can be informally revoked at any time, even with limited decision-making capacity. Nobody may be obliged to issue a directive in any way. Advance directives do not need notarisation or routine updating after certain time intervals. Provided that the patient, who is no longer mentally competent, has issued a lasting power of attorney, or provided that the patient has been appointed a healthcare proxy by the courts, this authorised surrogate must assert the patient's will. The role of the guardianship court is clarified: it only needs to be involved in cases of disagreement as to the patient's will. The new German law thus combines more legal certainty with a liberal emphasis on patient autonomy and flexible, adaptable regulations. (shrink)

Avery’s et al. ’s 1944 paper provides the first direct evidence of DNA having gene-like properties and marks the beginning of a new phase in early molecular genetics (with a strong focus on chemistry and DNA). The study of its reception shows that on the whole, Avery’s results were immediately appreciated and motivated new research on transformation, the chemical nature of DNA’s biological specificity and bacteria genetics. It shows, too, that initial problems of transferring transformation to other systems and prominent (...) criticism of its results nurtured skepticism. Avery’s experiment was downplayed and neglected particularly by many of those scientists who worked in the new fields of biochemical and biophysical genetics, genetic phage, and TMV research. This was not due to the fact that the implications of the paper could not be connected to generally accepted knowledge. Contrary to a widespread belief, the assumed uniformity of DNA as opposed to proteins was not used as an argument against the validity of Avery’s et al.’s finding. The indifference rather reflected, among other things, the disciplinary gap between the chemically oriented microbiologists and the old and new geneticists who remained committed to genetic and physical methods (in particular x-ray studies) and clung to the assumption that proteins were the sole carriers of biological specificity. The responses to Avery’s et al.’s paper show how different research interests in the areas between microbiology, genetics, and biochemistry interacted with the prejudices, dogmas, individual farsightedness or short-sightedness, and scientific authority during a pivotal period of early molecular biology. (shrink)